In many areas of technology, ceramic products are being used for their inert properties and heat resistance.
Many Rapid Prototyping processes have been developed in recent years and many more are currently being researched, but until recently, few of them have been used to fabricate ceramic objects.
One of the main challenges of the use of ceramic products with modern technologies is its reduction factor (shrinkage). Depending on the process used, drying, firing or hot pressing of a ceramic object can cause shrinkage as high as 20 percent. Such shrinkage can be a significant problem if the nature of the ceramic article requires precise dimensional control.
One of the first patents pertaining to the background of the present invention was obtained by Bredt et al. and is entitled “Method of three dimensional printing” (U.S. Pat. No. 5,902,441), May 11, 1999. This patent described the use of ink-jet print heads to deliver an aqueous solvent to a powder in cross-sections. This patent describes the basic technology of printers that may be used in accordance with the present invention, such as those commercially available from Z-corp of Burlington, Mass. A subsequent patent obtained by Bredt et al. and entitled “Method of three dimensional printing” (U.S. Pat. No. 7,087,109), Aug. 8, 2006 further describes the use of three-dimensional printer systems. Subsequent patents by Jialin Shen (U.S. Published Pat. Appl. 20020016387; 2002) and Kenneth Newell (U.S. Published Pat. Appl. 20040081573; 2004) describe means of producing more stable, stronger, and more durable RP objects through various combinations of binder and solvent. Newell's method produces a “green object,” an unfired ceramic negative for use as a mold for injected metal. Improvements in Newell's mold-making methods are found in subsequent patents by Bardes, Bruce Paul et al (U.S. Published Pat. Appls. 20040151935, 20040152581 and 20050252631; 2004 and 2005) and Lynch, Robert F. et al. (U.S. Published Pat. Appl. 20050281701; 2005).
An article entitled “Rapid Prototyping with Ceramics” by Elizabeth A. Judson & Thomas L. Starr of the Materials Science and Engineering of the Georgia Institute of Technology (found at http://www.pelcor.com/library/judson_starr/) explains the use of “Injection Molding and Stereolithography” for the creation of molds for casting purposes.
A publication entitled “The CAM-LEM Process” (found at http://dora.eeap.cwru.edu/camlem/camproc.html) explains how layers of ceramic material can be cut with the use of a computer assisted laser cutter and then stacked and fused in order to obtain a final ceramic article.
Notwithstanding these developments, there remains a need for methods of making shaped ceramics in an efficient manner while reducing the shrinkage attendant to prior art techniques. Some of the improvements sought to the prior art include apparatus, methods and compositions that are capable of producing ceramic precursors with high green strength and more accurate final ceramic shapes with a high degree of veracity to the desired shape, such as through the reduction in shrinkage and distortion. Ceramics produced in accordance with the present invention may also have relatively reduced porosity compared to ceramics from other methods.